Paper with higher oil repellency

ABSTRACT

This disclosure provides for a process for making an oil and grease resistant cellulosic material such as paper and paperboard, the process comprising applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate, and subsequently drying the treated cellulosic substrate to form an oil repellent cellulosic material. Fluorochemicals that can be used to modify the nanoparticles include fluoroalkylsilanes, ionic fluorochemicals, or fluorinated polyacrylate obtained by seeded emulsion polymerization of fluorinated acrylates on the nanoparticles. Paper, paperboard and cellulose fiber articles that have been modified by the disclosed processes have improved oil and grease resistance properties.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 61/713,354, filed Oct. 12, 2012, the disclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The invention relates to oil and grease resistant/repellent paper and methods for making oil and grease resistant paper.

BACKGROUND OF THE INVENTION

Paper is a composite material containing small, interconnected discrete fibers, which provides a highly porous structure. Paper typically is made from cellulose fibers, which are usually formed into a sheet on a fine screen from a dilute water suspension or slurry, so that it incorporates randomly distributed fibers and air voids. For example, the specific area of paper can be about 0.5-10 m²/g, in which the voids represent 25-70% of the paper volume, which leads to an apparent density of paper of less than about 0.8 g/cm³.

Just as paper products made from untreated cellulose fibers that become wet lose their strength rapidly due to water penetration, the porous structure of paper can also lead to its penetration by oil, grease, organic solvents, and the like. Conventionally, materials such as waxes, silicones, or fluorochemicals have been applied topically to cellulose fiber products to provide some measure of oil and grease resistance. However, environmental and health concerns about C8 telomer-based water and oil repellent products used in conventional fluorochemical treatments has required converting the C8 telomer fluorochemicals to C6 telomer and perfluoropolyether (PFPE) fluorochemicals, which are thought to have lower risk of degradation into products harmful to the environment. These latter fluorochemicals are somewhat less efficient at oil and grease resistance, and the conversion process itself is inefficient, costly, and time-consuming.

Therefore, there is a continuing need in the art for improved methods and compositions for imparting oil and grease resistance to paper and paper products, particularly those that involve the use of lower concentrations of fluorochemicals for environmental and cost improvements. Also it is desirable to further extend the effectiveness of fluorochemicals and to produce a paper or paperboard or cellulose fiber product with improved stiffness, print clarity, adhesion, release and friction characteristics while still retaining desirable oil and grease repellency and holdout attributes. This need is increasing with the increased demand for grease/oil resistant or repellent paper for use with bakery products, pet food packaging, instant and fast foods, and the like. Desirable methods would be applicable to a wide range of paper products and provide more environmentally benign manufacturing processes, while still maintaining efficient performance for oil and grease resistance.

SUMMARY OF THE INVENTION

According to this disclosure, there is provided a process for improving the grease- or oil-repellency of a cellulose material such as paper or paperboard, the process comprising treating or contacting a cellulose material with an aqueous dispersion comprising at least one modified nanoparticle component and at least one fluorochemical to form an oil-repellent cellulose material. Typically, the process can comprise applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and drying the treated cellulosic substrate to form an oil repellent cellulosic material. The fluorochemical can be selected from or can comprise at least one fluoroalkylsilane, cationic fluorochemical, or fluorinated polyacrylate.

In one aspect, the disclosed provides for combining in an aqueous medium a nanoparticle component and a fluorochemical such as a fluoroalkylsilane to form a homogeneous aqueous dispersion comprising fluorochemical surface-modified nanoparticles, and then contacting the homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles with a cellulosic substrate to form an oil repellent cellulosic material. The process can further comprise drying or curing oil-repellent or -resistant cellulose material once prepared. It has been discovered that the combination of both at least one nanoparticle component and at least one fluorochemical to form a fluorochemical surface-modified nanoparticle provides an unexpected improvement in the oil-repellent characteristics of the cellulose material, while still allowing a lower overall concentration of fluorochemical to impart the oil-repellency. Therefore, one aspect of the disclosure is that a more environmentally benign and lower cost process using lower concentrations of fluorochemicals may be possible, which still provides the desired oil-repellent properties.

While not intending to be theory-bound, it is believed that the least one nanoparticle component and at least one fluorochemical of the type disclosed herein, and combined as disclosed herein, work well because the inorganic nanoparticles and the fluorochemicals are obtained in separate processes and individually, have different affinities towards paper and paperboard. As a result of these different affinities, a separation can occur such that one component may penetrate the paper surface faster than the other component. To address this issue, this disclosure provides for the association of a fluorochemical with the rigid nanoparticle through chemical bonds, ionic bonds or polymerization on the inorganic/or organic seed particles, and forming such bonds can be achieved by selecting the fluorochemical from a fluoroalkylsilane, a cationic fluorochemical, or a fluorinated polymer such as a fluorinated polyacrylate, respectively. The resulting modified or functionalized particle appears to be a type of composite material that simultaneously delivers the fluorochemical and the nanoparticle and their respective influences, and thereby provides a “Lotus effect”. In one aspect, these fluorochemicals may be considered as “supported” in that they can interact with the rigid nanoparticles, depending on the nanoparticle composition, and this combined composition is added to the paper at the wet end, typically along with a retention aid, and/or at the size-press. When used at the size-press, the size-press solution contains starches or PVA, and the cellulosic support for the particles can be paper or board, made from hard wood and/or soft wood.

According to a further aspect, and while not intending to be bound by theory, it is thought that the combination of at least one nanoparticle component and at least one fluorochemical acts to alter the paper or paperboard (cellulose material) surface geometry and surface energy, which enhances the grease- and oil-repellency properties. In particular, it is thought that the specific fluorochemicals used in this process can modify the surface of the nanoparticles in a manner that allowed them to function in a manner that combines the useful attributes of the individual components in a synergistic fashion. Suitable nanoparticles include inorganic nanoparticles (such as silica, clay minerals, other inorganic nanoparticles), organic polymer nanoparticles (polystyrene, styrene acrylonitrile (SAN), and the like) having a glass transition temperature (Tg) greater than 100° C.; or combinations thereof.

In an exemplary aspect, according to this disclosure, there is provided a process for improving the grease- and oil-resistance or grease- and oil-repellency of a cellulosic material, such as paper, paperboard, and other cellulose-based materials, the process comprising: a) combining in an aqueous medium a nanoparticle component and a fluorochemical to form a homogeneous aqueous dispersion comprising fluorochemical surface-modified nanoparticles; and b) contacting the homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles with a cellulosic substrate to form an oil repellent cellulosic material. In a further exemplary aspect, there is provided a process for making an oil repellent cellulosic material, the process comprising: a) applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and b) drying the treated cellulosic substrate to form an oil repellent cellulosic material. When the fluorochemical is selected from or comprises a fluoroalkylsilyl compound, the process can comprise:

-   -   a) combining in an aqueous medium a nanoparticle component and a         fluoroalkylsilane to form a homogeneous aqueous dispersion         comprising fluoroalkylsilane surface-modified nanoparticles, the         fluoroalkylsilane having the formula:

[F(CF₂)_(n)CH₂CH₂]_(m)Si(OR)_(p),

wherein

-   -   n is 2, 3, or 4,     -   m is 4-p,     -   p is 1, 2, or 3, and     -   R is a C₁-C₆ hydrocarbyl or —C(O)R¹ wherein R¹ is independently         a C₁-C₆ hydrocarbyl;

and

-   -   b) contacting the homogeneous aqueous dispersion of         fluoroalkylsilyl surface-modified nanoparticles with a         cellulosic substrate to form an oil repellent cellulosic         material.

According to a further aspect of this disclosure, in order to obtain the homogeneous aqueous dispersion of fluorochemical surface modified nanoparticles, a process comprising the following steps may be employed:

-   -   a) combining in an aqueous medium a nanoparticle component and a         fluorochemical (for example a fluoroalkylsilane, a cationic         fluorochemical, or both) to form a heterogeneous mixture; and     -   b) allowing the nanoparticle component and the fluorochemical in         the heterogeneous mixture to interact or react until the         heterogeneous mixture forms a homogeneous aqueous dispersion of         fluorochemical surface-modified nanoparticles.         In this process for making an aqueous dispersion of         fluorochemical surface-modified nanoparticles, the step of         combining in an aqueous medium a nanoparticle component and a         fluorochemical can be carried out by, for example, combining an         aqueous dispersion of the nanoparticle component and the         fluorochemical.

The fluorochemicals used to surface-modify the nanoparticles can be cationic fluorochemicals, such that ionic interactions develop between the anionic inorganic nanoparticle and the cationic fluorochemical. However, anionic fluorochemicals can be used as well. For example, to use anionic fluorochemicals, the anionic nanoparticles can be treated first with a cationic polymer, such as polyamine, polyamidoamine, polyamidoamine epichlorohydrine (PAE), polyDADMAC (polydiallyldimethylammonium chloride), and/or a cationic copolymer of acrylamide. If desired, the addition of the anionic fluorochemical to a cellulosic substrate such as paper can be performed in one step if desired, wherein the paper can be treated with anionic nanoparticles previously modified with a cationic polymer and then an anionic fluorochemical. Alternatively, the addition of the anionic fluorochemical to a cellulosic substrate such as paper can be performed in two steps if desired, wherein the anionic nanoparticles treated with a cationic polymer are used to treat the paper and then the dried paper is treated in a second step with anionic fluorochemicals.

Once the a cellulosic substrate has been treated or contacted with a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to form an oil repellent cellulosic material, the process can further comprise curing the treated or contacted cellulose material. It has been discovered that the disclosed method provides an unexpected improvement in the oil-repellent characteristics of the cellulose material, while still allowing a lower overall concentration of fluorochemical to impart the oil-repellency. Therefore, it appears that the at least one nanoparticle component acts as a type of extender for the fluorochemical such that lower, more environmentally benign, and lower cost concentrations of fluorochemical can be used to provide the desired oil-repellent properties.

The following detailed description and appended claims set forth further embodiments and aspects of this disclosure.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with one aspect of the disclosed composition, certain processes have been developed in which novel nanoparticle compositions, particularly inorganic nanoparticle compositions, which have been surface modified by a bi-phasic reaction with liquid fluoroalkylsilane (FAS) reagents in an aqueous medium or by intereaction with cationic fluorochemical reagents or by contacting or forming fluorinated polyacrylates or other polymers with or at the nanoparticle surface, which can be used to treat a cellulosic material and impart excellent oil-repellent properties. The aqueous dispersions of the disclosed composition typically are monophasic, optically transparent and stable without significant aggregation or precipitation and with little or no additional solvents or surfactants. In one aspect, for example, the disclosed composition used in the treating process can comprises an aqueous dispersion of fluoroalkylsilyl surface modified nanoparticles, wherein the nanoparticles comprise or are selected from at least one member selected from the group consisting of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay, polystyrene, styrene acrylonitrile (SAN), or combinations thereof, and wherein the fluoroalkylsilyl surface-functionalizing moiety can be described as [F(CF₂)_(n)CH₂CH₂]_(m)Si(O—)_(p), wherein n is 2, 3, or 4; m is 4-p; and p is 1, 2, or 3. If desired, the composition can further comprise an additional non-fluorinated alkylsilyl surface-functionalizing moiety bonded to the surface of the nanoparticle having the formula[H(CH₂)_(x)]_(y)Si(O—)_(z), wherein x is an integer from 1 to 12; y is 4-z; and z is 1, 2, or 3. For example, the additional component can be methylsilyl.

According to a further aspect, articles comprising the fluorochemical surface-modified nanoparticles are disclosed, for example, the article can include paper, paperboard or cellulose based articles, and the article can exhibit improved resistance to both grease and oil. Treated paper, paperboard, and cellulose based products also show improved stiffness, print clarity, adhesion, release and friction characteristics over conventional fluorochemical or silicone treated papers and paperboard and cellulose fiber products.

According to this disclosure, there is provided a process for making an oil repellent cellulosic material, the process comprising:

-   -   a) applying a homogeneous aqueous dispersion of fluorochemical         surface-modified nanoparticles to a cellulosic substrate to form         a treated cellulosic substrate; and     -   b) drying the treated cellulosic substrate to form an oil         repellent cellulosic material.         The fluorochemical used in this process can comprises at least         one fluoroalkylsilane, cationic fluorochemical, or fluorinated         polyacrylate.

In a further aspect, when the fluorochemical is a fluoroalkylsilane, there is provided a process for improving the grease- or oil-resistance of a cellulosic material, such as paper, paperboard, and other cellulose-based materials, the process comprising:

a) applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and

b) drying the treated cellulosic substrate to form an oil repellent cellulosic material;

wherein the fluorochemical used to modify the surface of the nanoparticles comprises at least one fluoroalkylsilane having the formula

[F(CF₂)_(n)CH₂CH₂]_(m)Si(OR)_(p),

wherein:

-   -   n is 2, 3, or 4;     -   m is 4-p;     -   p is 1, 2, or 3; and     -   R is a C₁-C₆ hydrocarbyl or —C(O)R¹ wherein R¹ is independently         a C₁-C₆ hydrocarbyl.         If the initial step of preparing the aqueous dispersion of         fluoroalkylsilyl surface-modified nanoparticles is undertaken,         the process can comprise:     -   a) combining in an aqueous medium a nanoparticle component and a         fluoroalkylsilane to form a homogeneous aqueous dispersion         comprising fluoroalkylsilane surface-modified nanoparticles, the         fluoroalkylsilane having the formula:

[F(CF₂)_(n)CH₂CH₂]_(m)Si(OR)_(p),

wherein

-   -   n is 2, 3, or 4,     -   m is 4-p,     -   p is 1, 2, or 3, and     -   R is a C₁-C₆ hydrocarbyl or —C(O)R¹ wherein R¹ is independently         a C₁-C₆ hydrocarbyl; and     -   b) contacting the homogeneous aqueous dispersion of         fluoroalkylsilyl surface-modified nanoparticles with a         cellulosic substrate to form an oil repellent cellulosic         material.

According to a further aspect of this disclosure, if the step of preparing the aqueous dispersion of fluoroalkylsilyl surface-modified nanoparticles is undertaken, the process can comprise:

-   -   a) combining in an aqueous medium a nanoparticle component and a         fluoroalkylsilane to form a heterogeneous mixture, the         fluoroalkylsilane having the formula:

[F(CF₂)_(n)CH₂CH₂]_(m)Si(OR)_(p),

wherein

-   -   n is 2, 3, or 4,     -   m is 4-p,     -   p is 1, 2, or 3, and     -   R is a C₁-C₆ hydrocarbyl or —C(O)R¹ wherein R¹ is independently         a C₁-C₆ hydrocarbyl;

and

-   -   b) allowing the nanoparticle component and the fluoroalkylsilane         in the heterogeneous mixture to react until the heterogeneous         mixture forms a homogeneous aqueous dispersion of         fluoroalkylsilane surface-modified nanoparticles.         In this process for making an aqueous dispersion of         fluoroalkylsilyl surface-modified nanoparticles, the step of         combining in an aqueous medium a nanoparticle component and a         fluoroalkylsilane can be carried out by, for example, combining         an aqueous dispersion of the nanoparticle component and the         fluoroalkylsilane.

In yet another aspect, a modified substrate is disclosed. The modified substrate comprises a fluorochemical surface-modified nanoparticle on at least one surface of the substrate, wherein the nanoparticle and the fluorochemical are as disclosed herein. If desired, the substrate can further comprise additional non-fluorinated moieties, such as non-fluorinated alkylsilyl moieties also as disclosed herein. When the substrate comprises the additional non-fluorinated alkylsilyl component moiety, such as trimethylsilyl, the nanoparticles that work particularly well can be selected from silica, zirconia, titania, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof. The substrate itself a cellulose based substrate, typically a paper or paperboard.

In a further aspect, a process of making an oil and grease resistant cellulosic material is disclosed. The process can comprises (i) applying an aqueous dispersion of fluorochemical surface modified nanoparticles to the substrate, wherein the aqueous dispersion comprises at least one of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures; and wherein the fluorochemical is as disclosed herein; and (ii) drying the substrate. The fluorochemical surface modified nanoparticles can be applied either on one or more surfaces or on the wet end so that it is in the interior of the substrate or a combination of these.

The nanoparticle according to this disclosure, in an aspect, can comprise silica, titania, zirconia, layered magnesium silicates, aluminosilicates, clays and mixtures thereof, for example the clay can be a synthetic clay such as hectorite clay. In another aspect, a useful combination of nanoparticles for surface modification can be, for example, a mixture of synthetic hectorite clay and silica.

When the fluorochemical provides a fluoroalkylsilyl moiety, such fluoroalkylsilyl moieties can be covalently bonded to the nanoparticle surfaces. The fluorochemical surface-modified nanoparticles, including the fluoroalkylsilyl surface-modified nanoparticles, can be present at a concentration in the range of from about 0.01% to about 50% by weight of the total composition of the dispersion, for example in the range of from about 1% to about 40% by weight, including about 1% to about 8% by weight of the total composition. In a further aspect, the fluorochemical surface-modified nanoparticles can be present at a concentration (by weight of the total composition of the dispersion) of about 0.01%, about 0.02%, about 0.05%, about 0.1%, about 0.2%, about 0.5%, about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 12%, about 15%, about 18%, about 20%, about 25%, about 30%, about 30%, about 40%, about 50%, or about 50%, or any range between any of these concentrations. For example, stable aqueous dispersions of fluorochemical surface modified nanoparticles wherein the nanoparticles are synthetic hectorite clay can be formed at a concentration in the range of from about 0.01% to about 12% by weight of the total composition, including about 1% to about 8% by weight of the total composition.

Depending on the final use and the particular cellulose based substrate to be treated, the dispersion of the present invention can be diluted for more efficient application or to control the level of moisture imparted in the treatment process. Again, depending on the nature of the substrate that is to be treated, its intended use and the process of manufacture, other chemistries as may be known in the art can be combined with the aqueous dispersion of the instant invention at suitable concentration ranges.

The composition can further comprise a fluorinated resin emulsion, an alkylated inorganic nanoparticle having no fluorine, and/or at least one member selected from a wetting agent, fluorochemical resin, surfactant, silicones, optical brighteners, antibacterial components, anti-oxidant stabilizers, coloring agents, light stabilizers, UV absorbers, wetting agents, starch, polyvinyl alcohol, retention aids and wet strength aids and mixtures thereof. Optionally, the composition can be blended with additional wetting agents, anti-soil agents, fluorochemical resins, surfactants or mixtures thereof, as known in the art, in order to simplify the manufacturing process at hand. While the aqueous dispersion is generally compatible, it is naturally desirable to avoid the addition of materials that would coalesce or precipitate the nanoparticles or otherwise diminish efficacy or utility.

In an aspect, the disclosed dispersions are found to be surprisingly stable and exist indefinitely at moderately high concentrations as transparent aqueous mixtures in spite of the intrinsically hydrophobic nature of fluorochemical modified surfaces, such as fluoroalkylated surfaces. The compositions can be useful to treat soft paper, paperboard and cellulose fiber articles, either applied to one or both sides on the dry end such as a size press or coater, or to the wet end such that the chemistry is throughout the article, or in both the dry and wet ends of the papermaking process, to impart several valuable attributes. Paper, paperboard and cellulose fiber articles treated with the various dispersions described have also been shown to have increased oil and grease repellency.

Fluoroalkylsilyl Surface-Modified Nanoparticles. The fluoroalkylsilanes that can be used to surface modify the nanoparticles and provide the fluoroalkylsilyl surface-modified nanoparticles, include but are not limited to fluoroalkylsilane having the formula:

[F(CF₂)_(n)CH₂CH₂]_(m)Si(OR)_(p),

wherein

-   -   n is 2, 3, or 4,     -   m is 4-p,     -   p is 1, 2, or 3, and     -   R is a C₁-C₆ hydrocarbyl or —C(O)R¹ wherein R¹ is independently         a C₁-C₆ hydrocarbyl.

In an aspect, there is provided a process for making and using an aqueous dispersion of fluoroalkylsilyl surface-modified nanoparticles, the process typically comprising: a) combining in an aqueous medium a nanoparticle component and a fluoroalkylsilane to form a heterogeneous mixture, and b) allowing the nanoparticle component and the fluoroalkylsilane in the heterogeneous mixture to react until the heterogeneous mixture forms a homogeneous aqueous dispersion of fluoroalkylsilane surface-modified nanoparticles. In this disclosed process, the fluoroalkylsilane surface-modified nanoparticles can comprise fluoroalkylsilyl moieties having the formula [F(CF₂)_(n)CH₂CH₂]_(m)Si(O—)_(p). The step of combining in an aqueous medium a nanoparticle component and a fluoroalkylsilane can be carried out by preparing an aqueous dispersion of the nanoparticle component, followed by combining or adding the fluoroalkylsilane, as exemplified in the Examples provided herein.

Also in this disclosed process, the step of combining in an aqueous medium a nanoparticle component and a fluoroalkylsilane can further comprises combining a non-fluorinated alkylsilane having the formula:

[H(CH₂)_(x)]_(y)Si(OR²)_(z)

or

[H(CH₂)_(x)]_(y)Si(X)_(z),

wherein

-   -   x is an integer from 1 to 12;     -   y is 4-z;     -   z is 1, 2, or 3;     -   R² in each occurrence is a C₁-C₆ hydrocarbyl or —C(O)R³ wherein         R³ is independently a C₁-C₆ hydrocarbyl; and

X in each occurrence is independently halide or R².

In this aspect, the fluoroalkylsilane surface-modified nanoparticles can comprise non-fluorinated alkylsilyl moieties having the formula [H(CH₂)_(x)]_(y)Si(O—)_(z) or [H(CH₂)_(x)]_(y)Si(−)_(z) or [H(CH₂)_(x)]_(y)Si (O—)_(z)(—)_(q), wherein “—” is a direct silicon-nanoparticle bond and y+z+q is 4, along with the fluoroalkylsilyl moieties having the formula [F(CF₂)_(n)CH₂CH₂]_(m)Si(O—)_(p).

According to a further aspect, this disclosure provides for a process for making oil repellent cellulosic material, the process comprising contacting or treating a cellulosic substrate with the an aqueous dispersion of fluoroalkylsilyl surface-modified nanoparticles prepared as diclosed herein. For example, there is disclosed a process for making oil repellent cellulosic material, the process comprising contacting a homogeneous aqueous dispersion of fluoroalkylsilyl surface-modified nanoparticles with a cellulosic substrate to form an oil repellent cellulosic material, in which the aqueous dispersion of fluoroalkylsilyl surface-modified nanoparticles is provided by combining in an aqueous medium a nanoparticle component and a fluoroalkylsilane to form a homogeneous aqueous dispersion comprising fluoroalkylsilane surface-modified nanoparticles, the fluoroalkylsilane having the formula [F(CF₂)_(n)CH₂CH₂]_(m)Si(OR)_(p), as set forth herein. The step of combining in an aqueous medium a nanoparticle component and a fluoroalkylsilane can further comprises combining a non-fluorinated alkylsilane having the formula [H(CH₂)_(x)]_(y)Si(OR²)_(z), as disclosed herein.

Suitable nanoparticle components used according to this disclosure include at least one member selected from silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures or combinations thereof. For example, a further aspect provided is a process for making a fluoroaklysilyl surface modified nanoparticle selected from silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay, the process comprising: (i) creating an aqueous dispersion of at least one member selected from the group consisting of silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof; (ii) adding a water immiscible fluoroalkylsilane reagent to the aqueous dispersion to form a heterogeneous mixture where the fluoroalkylsilane reagent is: (F(CF₂)_(n)CH₂CH₂)_(m)Si(OR)_(p), where n is 2, 3 or 4, p is 1, 2 or 3, m is (4-p), and R is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and —C(O)CH₃; and (iii) mixing or stirring the heterogeneous mixture or allowing it to stand until it forms a homogeneous aqueous dispersion of fluoroaklysilane surface-modified nanoparticles. In one example, the fluoroalkylsilane can be (F(CF₂)_(n)CH₂CH₂)_(m)Si(O—R)_(p), where n can be 4, p can be 3 when m is 1 and R can be selected from methyl and ethyl. In a further example, the nanoparticle can comprise silica, titania, zirconia, layered magnesium silicates, aluminosilicates, clays and mixtures thereof, for example the clay can be a synthetic hectorite clay, for example a mixture can be synthetic hectorite clay and silica. The fluoroalkylsilane moieties can be covalently bonded to the nanoparticle surface, creating a fluoroalkylsilyl moiety.

The process of making an oil repellent cellulosic material also may comprise: a) applying or contacting a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and b) drying the treated cellulosic substrate to form an oil repellent cellulosic material, and can further comprise adding a fluorinated resin emulsion to the aqueous dispersion prior applying the aqueous dispersion to the cellulosic substrate. Additionally, the process can further comprise including an alkylated inorganic nanoparticle having no fluorine in the aqueous dispersion prior applying the aqueous dispersion to the cellulosic substrate. Moreover, the process can further comprise adding at least one member selected from the group consisting of a wetting agent, anti-soil agent, fluorochemical resin, surfactant and mixtures thereof prior applying the aqueous dispersion. Optionally, a compound having the formula:

[H(CH₂)_(x)]_(y)Si(OR²)_(z)

or

[H(CH₂)_(x)]_(y)Si(X)_(z),

wherein

-   -   x is an integer from 1 to 12;     -   y is 4-z;     -   z is 1, 2, or 3;     -   R² in each occurrence is a C₁-C₆ hydrocarbyl or —C(O)R³ wherein         R³ is independently a C₁-C₆ hydrocarbyl; and     -   X in each occurrence is independently halide or R²;         can be used to contact the nanoparticle before, during, or after         contacting the nanoparticle with the fluoroalkylsilane. That is,         the compound having the formula [H(CH₂)_(x)]_(y)Si(OR²)_(z) or         [H(CH₂)_(x)]_(y)Si(X)_(z) can be added at substantially the same         time or before, or after the addition of the fluoroalkylsilane         in contacting the nanoparticle. For example, X in this optional         compound can be selected from methoxy, ethoxy, propoxy, butoxy,         acetoxy, and chloride leaving groups. A recirculation pump and         static mixer may be used in the disclosed process to further         increase the interfacial contact between the immiscible         fluoroalkylsilane and nanoparticles.

Also as an example, according to embodiments, the fluoroalkylsilane reactant used in step (ii) of the process to create the fluoroalkylsilyl surface modified nanoparticles can be (F(CF₂)_(n)CH₂CH₂)_(m)Si(O—R)_(p), where n is 2, 3 or 4; where p is 1, 2 or 3; where (m+p)=4; and where R is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and —C(O)CH₃. In other embodiments, the fluoroalkyl moiety of the alkylsilane reactant can be a perfluoroalkane of two to four carbons in length, for example a four carbon nanofluoroalkane (n is 4), where m is 1 and p is 3, and where R is either methyl or ethyl. Extended perfluoroalkane chains can be used to achieve greater degrees of hydrophobicity in treated substrates. However, fluoroalkylsilyl reagents having perfluoroalkane chains longer than four carbon atoms (n value greater than 4) are less suitable for making the disclosed aqueous dispersions as the addition of undesirable levels of solvents or surfactants would be required to stabilize both reactants and product dispersions in the disclosed process.

In one aspect of the disclosed process, 1,1,2,2-tetrahydro-nonafluorohexyl trimethoxysilane can be added slowly with stirring to a 25% (w/w) aqueous dispersion of colloidal silica (20 nm particles) with pH 9 to form a liquid-liquid emulsion of cloudy appearance. Optionally, a recirculation pump and static mixer can be used with or without the mechanical stirrer to increase interfacial contact of the FAS with the colloidal silica if desired. The fluoroalkylsilyl minor liquid phase is consumed with stirring over a period of hours gradually reducing to a single liquid phase dispersion that remains stable in the absence of stirring. The resulting stable aqueous dispersion contains dispersed silica nanoparticles that have a covalently bonded hydrophobic layer on the particle surface, and this aqueous dispersion is used to treat or contact the cellulosic substrate.

In accordance with another aspect of the disclosed process, 1,1,2,2-tetrahydro-nonafluorohexyl trimethoxysilane (the “FAS” or fluoroalkylsilyl reagent) can be used (for example, added slowly to) a 5% (w/w) aqueous dispersion of synthetic hectorite clay nanoparticles sold by the trade name Laponite® RDS from Rockwood Additives Ltd. To prepare the fluoroalkylsilyl surface-modified nanoparticle. Optionally, the dispersion of the present invention can be blended with fluorinated resin emulsions or with dispersions of alkylated inorganic nanoparticles having no fluorine. For example, the dispersions of the fluoroalkyl modified clay nanoparticles described above can be blended with an aqueous dispersion of colloidal silica nanoparticles which have been surface modified with methyltrimethyoxysilane (MTMS) so that the resulting aqueous dispersion comprises two distinctly different nanoparticles.

Also disclosed are substrates and processes for making and using the fluoroalkylsilyl surface modified nanoparticles. The substrate can comprise a fluoroalkylsilyl surface-modified nanoparticle on at least one surface, wherein the nanoparticle comprises at least one member selected from the group consisting of: titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof, and wherein the fluoroalkylsilyl is: (F(CF₂)_(n)CH₂CH₂)_(m)Si(O—)_(p), where n is 2, 3 or 4, p is 1, 2 or 3, and m is (4-p). The nanoparticle of the present invention can comprise titania, zirconia, layered magnesium silicates, aluminosilicates, clays and mixtures thereof, for example the clay can be a synthetic hectorite clay, for example a mixture can be synthetic hectorite clay and zirconia.

In embodiments, the fluoroalkylsilyl surface-modified nanoparticle can comprise (F(CF₂)_(n)CH₂CH₂)_(m)Si(O—)_(p), where n can be 4, p can be 3 when m is 1, in which the fluoroalkylsilyl moiety can be covalently bonded to the nanoparticle surface. The substrate can have pores having an average diameter in the range of from about 100 to about 100,000 nanometers. The fluoroalkylsilane surface modified nanoparticle can form at least one layered structure on the substrate, wherein the layered structure has a thickness of about 10,000 nanometers or less, and a width and length of about 100,000 nanometers or more. The substrate can optionally comprise a component moiety bonded to the surface of the nanoparticle having the formula [H(CH₂)_(x)]_(y)Si(O—)_(z), wherein x is an integer from 1 to 12, y is 4-z, and z is 1, 2, or 3. When the nanoparticle comprises the optional component moiety, the nanoparticle can include silica, titania, zirconia, layered magnesium silicates, aluminosilicates, clays and mixtures thereof.

According to a further aspect, there is provided a process for making an oil repellent cellulosic material, the process comprising: a) applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and b) drying the treated cellulosic substrate to form an oil repellent cellulosic material; wherein the fluorochemical can comprise or be selected from at least one cationic fluorochemical. In this aspect, the ionic bonds can be formed between the anionic nanoparticles and the cationic fluorochemicals.

Cationic Fluorochemicals. This disclosure also provides for a process for making an oil repellent cellulosic material, the process comprising the steps of: a) applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles (also termed nanoparticles that are surface-modified by a fluorochemical) to a cellulosic substrate to form a treated cellulosic substrate; and b) drying the treated cellulosic substrate to form an oil repellent cellulosic material, in which the fluorochemical can comprise or can be selected from at least one cationic fluorochemical. In this aspect, suitable cationic fluorochemicals can comprise or be selected from compounds such as those disclosed in GB 1,214,528, which is incorporated by reference herein in its entirety. For example, the cationic fluorochemical can be a fluorinated cationic polyamidoamine such as a protonated, an alkylated, or an epoxidized amide-amine fluoro compound, resulting from a protonation reaction, an alkylation reaction, or the reaction of an epihalohydrin with an intermediate amide-amine fluoro compound of the formula:

Z—(X)_(y)—C(O)—NH[(CH₂)_(m)—NH]_(n)C(O)—(X)_(y)—Z,

wherein

Z is a radical selected from perfluoro alkyl radicals of the formula C_(s)F_((2s+1)), where s is an integer having a value of from 3 to 20 inclusive, and cycloperfluoro alkyl radicals of the formula C_(t)F_((2t−1)), where t is an integer having a value of from 4 to 6 inclusive;

X is a radical selected from straight chain alkylene radicals of the formula (CH₂)_(p), where p is an integer having a value of from 2 to 14 inclusive, cycloaliphatic radicals, bridged cycloaliphatic radicals, —CH═CH—(CH₂)_(b)—O—(CH₂)₂—, —CH₂—CH₂—(CH₂)_(b)—O—(CH₂)₂—, —CH═CH—(CH₂)_(b)—S—(CH₂)₂—, —CH₂—CH₂—(CH₂)_(b)—S—(CH₂)₂— radicals, where b is zero or an integer of from 1 to 14 inclusive and —SO₂—N(R)—(CH₂)_(q)— radicals, where R is an alkyl radical containing from 1 to 6 carbon atoms and q is an integer of from 2 to 12 inclusive;

y is 0 or 1;

m is an integer of from 2 to 6 inclusive;

and n is an integer of from 2 to 100 inclusive.

For example, the cationic fluorochemical can be an epoxidized amide-amine fluoro compound, resulting from the reaction of an epihalohydrin with the intermediate amide-amine fluoro compound disclosed above, having the formula Z—(X)_(y)—C(O)—NH[(CH₂)_(m)—NH]_(n)—C(O)—(X)_(y)—Z. While not intending to be bound by theory, it is thought that the product initially resulting from the reaction between the epihalohydrin and the fluoro intermediate described immediately above may corresponds to the following formula:

wherein:

A is a halogen radical and Z, X, y, m and n are as previously defined. However, as the reaction proceeds, the above described initial reaction product condenses through its epoxide group with additional quantities of the epihalohydrin, thereby likely assuming a more complex structure.

The intermediate amide-amine fluoro compound of the formula Z—(X)_(y)—C(O)—NH[(CH₂)_(m)—NH]_(n)—C(O)—(X)_(y)—Z can be prepared by admixing and subsequently reacting a fluoro acid corresponding to the formula Z—(X)_(y)—C(O)OH with at least one polyamine of the formula H₂N—[(CH₂)_(m)—NH]_(n)H, wherein Z, X, y, m and n are as previously defined.

For example, suitable cationic fluorochemicals include those generated from perfluorooctanoic acid reacting with tetraethylenepentamine, and then with epichlorohydrin, to provide the cationic fluorochemical as illustrated in the following structure:

In this structure, the amide nitrogen is no longer available for protonation. In order to have the right hydrophilic-hydrophobic balance, more amide may be used after the fluorocarbon tail is attached. Also as disclosed, the alkylation with fluorinated epoxides is used to prepare the azetidinium moieties.

In one aspect, suitable fluoro carboxylic acids (Z—(X)_(y)—C(O)OH) used to prepare the cationic amido-amine fluoro compounds include, but are not limited to: perfluorobutanoic acid, (C₃F₇COOH); perfluorooctanoic acid (C₇F₁₅COOH); omega-perfluoroheptyl pentanoic acid (C₇F₁₅(CH₂)₄COOH); omega-perfluoroheptyl undecanoic acid (C₇F₁₅(CH₂)₁₀COOH); perfluoroheptyl methyl cyclobutane carboxylic acid; perfluoroheptyl substituted norbornene carboxylic acid; omega-perfluoroheptyl-beta-allyloxy-propionic acid (C₇F₁₅—CH═CHCH₂—O—(CH₂)₂COOH); omega-perfluoroheptyl-beta-propoxypropionic acid (C₇F₁₅—(CH₂)₃—O—(CH₂)₂COOH); omegaperfluoroheptyl-beta-allylthiopropionic acid (C₇F₁₅—CH═CHCH₂—S—(CH₂)₂COOH); omega-perfluorohepryl-beta-propylthiopropionic acid (C₇F₁₅—(CH₂)₃—S—(CH₂)₂COOH); and, omega-(N-methyl)-perfluoroheptanesulfonamide hendecanoic acid (C₇F₁₅—SO₂—N(CH₃)—(CH₂)₁₀—COOH).

According to a further aspect, the polyamine compounds applicable for use in preparing the cationic amido-amine fluoro compounds include, but are not limited to H₂N—[(CH₂)_(m)—NH]₄H wherein m is an integer of from 2 to 6 inclusive and n is an integer of from 2 to 100 inclusive, and can include combinations of compounds according to this formula. Thus, among the applicable polyamines are included: diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and bis-hexamethylenetriamine, although these representative compounds are only exemplary. More than one of the polyamines corresponding to the above formula may be simultaneously utilized in the reaction system. If desired, crude residues containing mixtures of amines as the polyamine starting material can be employed. Moreover, both linear and branched structures of the polyamine are envisioned. For example, when the polyamine compound contains two or more primary amine groups and the value of n exceeds about 8, it is likely that the resulting polyamine will exhibit a branched structure, such branched polyamines also being deemed readily applicable for use according to this disclosure.

All available epihalohydrins, including epichlorohydrin and epibromohydrin, may be utilized in accordance with this disclosure, with epichlorohydrin being preferred for reasons of economy and availability. Conditions under which the amide-amine fluoro compound can be epoxidized from the reaction of an epihalohydrin include those conditions as disclosed in GB 1,214,528, which is incorporated by reference herein in its entirety.

Also by way of example, suitable cationic fluorochemical for use according to this disclosure include those provided in U.S. Pat. No. 4,344,993, which is incorporated herein by reference in its entirety. For example, the “ionic perfluorocarbons” described in U.S. Pat. No. 4,344,993 can be used. These ionic perfluorocarbons that can be suitably employed include organic compounds generally represented by the formula:

R_(f)Z,

wherein R_(f) is a saturated fluoroaliphatic moiety containing a F₃C-moiety and Z is a ionic moiety or a potentially ionic moiety. The fluoroaliphatic moiety can typically contain 3 to 20 carbons wherein substantially all are fully fluorinated, preferably from about 3 to about 10 of such carbons. This fluoroaliphatic moiety may be linear, branched or cyclic, preferably linear, and may contain an occasional carbon-bonded hydrogen or halogen other than fluorine, and further may contain a divalent sulfur or oxygen atom or a trivalent nitrogen atom bonded only to carbon atoms in the skeletal chain. More preferred are those linear perfluoroaliphatic moieties represented by the formula:

C_(n)F_(2n+1),

wherein n can be from about 3 to about 12, for example, from 5 to 10. Ionic or potentially ionic moieties advantageously further include those represented by the following formulas:

wherein:

-   -   R is hydrogen or hydrocarbyl such as lower alkyl having 1-3         carbons;     -   R′ is hydrocarbylene or oxyhydrocarbylene such as alkylene         having 1 to 6 carbons, arylene, oxyarylene, aralkylene or         similar divalent hydrocarbon or oxyhydrocarbon moiety;     -   each R″ is individually hydrogen, hydrocarbyl such as lower         alkyl having 1 to 5 carbons or hydroxyhydrocarbyl; and     -   X⁻ is an anion, especially an inorganic anion such as halide,         sulfate or carboxylate such as acetate; and     -   M⁺ is a cation such as an alkali metal cation or ammonium.

For example, in one aspect, the suitable cationic fluorochemical can be a cationic perfluorocarbon, including for example, 3-[((heptadecylfluorooctyl)sulfonyl)amino]-N,N,N-trimethyl-1-propanaminium iodide; 3-[((heptadecylfluorooctyl)carbonyl)amino]-N,N,N-trimethyl-1-propanaminium chloride, and/or a cationic perfluorocarbon sold by duPont under the tradename Zonyl™ FSC. Examples of other preferred cationic perfluorocarbons, as well as methods of preparation, are those listed in U.S. Pat. No. 3,775,126.

Additional further examples of cationic fluorochemicals include but are not limited to those provided in U.S. Pat. No. 6,951,962, which is incorporated herein by reference in its entirety. For example, suitable cationic fluorochemicals include those compounds having an oleophobic and hydrophobic fluorochemical group, which is substituted with an alkyl chain which has a hydrophilic group, where the fluorochemical portion of the fluorochemical group is further characterized as a monovalent, perfluorinated, alkyl or alkenyl, straight, branched or cyclic organic radical having three to twenty fluorinated carbon atoms, and which can be interrupted by divalent oxygen or sulfur atoms if desired.

In an aspect, suitable cationic fluorochemical compounds include those that contains both a polyamine functionality and fluorinated groups. For example, the polyamine can provide a type of molecular scaffolding upon which the fluorinated group and the cationic functionality are included or assembled. The polyamine functionality also can allow the nitrogens to be substituted with four groups such that they have a cationic character which aids in their function in accordance with the disclosure, for example, allows for interaction with the negatively charged nanoparticles. While not theory bound, the fluorinated groups included in the cationic fluorochemical compounds may reduce the surface energy to the point that oil and grease will not wet the cellulosic substrate to which the homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles is applied. Thus, the low free surface energies are thought to make them particularly effective at repelling low surface energy materials such as oil and grease, thus repelling these substances from a treated substrate.

In accordance with an aspect, the cationic fluorochemical compounds can include or be selected from those disclosed in U.S. Pat. No. 6,951,962, which is incorporated herein by reference in its entirety. For example, suitable cationic fluorochemicals include those having the following structures:

wherein:

-   -   R⁸, R⁹, R¹⁰, R¹¹, R¹² are selected from J, H, —(CH₂)₁₋₆H,         —(CH₂CH₂O)₁₋₁₀H, —(CH₂CHOH)₁₋₁₀CH₃, —CH(CH₃)CH₂OH,         —CH₂CH(OH)CH₂Cl,

—CH₂CH(OH)CH₂OH, —CH₂CO₂ ⁻M⁺ (M is a group 1 or 2 metal), —(CH₂)₁₋₆NH_(2,1,0)(R⁸)_(0,1,2),

-   -   wherein any two of R⁸, R¹⁰, R¹¹, or R¹² can be the same carbon         chain,     -   R⁷ is selected from H, —CH₂CH(OH)CH₂, which can be cross-linked         to nitrogen on K or L or M on a different fluoro(hydroxyl)alkyl,         polyalkyl amino halohydrin or organo sulfonate, where at least         one of R⁸, R⁹, R¹⁰, R¹¹, R¹² is a fluorochemical as denoted by         “J”, and J is selected from the following moieties:

wherein, according to the conventional rules of chemical valence:

-   -   A is selected from —(CH₂)₁₋₉—, —CH₂ CHI(CH₂)₁₋₉BCH₂—,         —CH═CH(CH₂)₁₋₉BCH₂—, —(CH₂)₁₋₁₁BCH₂—, —(CH₂)₁₋₂B(CH₂)₁₋₁₀BCH₂—,         where B is selected from O, CO₂, CO₂[(CH₂)₁₋₂O]₁₋₁₀, OCH₂ CO₂,         OCH₂ CO₂ CO₂ [(CH₂)₁₋₂O]₁₋₁₀, S, SO₂, SCH₂CO₂, C(O)S,         SCH₂C₂O[(CH₂)₁₋₂O]₁₋₁₀, S[(CH₂)₁₋₂O]₁₋₁₀, S(O)NR′, C(S)NR′,         S(O)NR′CH₂CH₂O, C(O)NR′, OCH₂C(O)NR′, OPO₃, NR′, SCH₂C(O)NR′,         —N(R)CH₂CO₂, where R′ is selected from H, —(CH₂)₁₋₆;     -   R is selected from H, —(CH₂)₁₋₆H;     -   R_(F) is selected from F(CF₂)₄₋₁₈, CF₃CF(CF₃)(CF₂)₃₋₅, CF₃CF₂         CF(CF₃)(CF₂)₃₋₅, H(CF₂)₄₋₁₈, HCF₂CF(CF₃)(CF₂)₃₋₅,         HCF₂CF₂CF(CF₃)(CF₂)₃₋₅, cycloperfluoroalky radicals of the         formula C₂F_((2z−1)) wherein z is an integer from 4-6 inclusive;     -   n, p, q, s, t, v, and w are integers;     -   p is 0 or 1;     -   n is 1-6;     -   v+q+w+s=an integer from 3 to about 1000;     -   q, w, s each may be zero if desired;     -   t is w+s;     -   Q is selected from Cl⁻, Br⁻, I⁻, CH₃C₆H₄SO₂ ⁻, CH₃SO₂ ⁻, and the         like; and     -   K, L and M are randomly distributed along the polyamine and T is         an amine on the end of the polyamine chain.

In accordance with a further aspect, the use of anionic fluorochemicals is possible because of ionic bonds between anionic nanoparticles and anionic fluorochemicals can be established through an intermediate cationic polymer. For example, the anionic nanoparticles are modified first with a cationic non-fluorinated polymer, such as polyamines, polyamidoamines, polyamidoamine epichlorohydrine (PAE), polyDADMAC, cationic polyacrylamide, and combinations thereof. The anionic fluorochemicals then can be used to form the fluiorochemical surface modified nanoparticles.

Fluorinated Emulsion Polymers. In accordance with a further aspect, there is provided a process for making an oil repellent cellulosic material, the process comprising: a) applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and b) drying the treated cellulosic substrate to form an oil repellent cellulosic material; wherein the fluorochemical comprises at least one fluorinated polyacrylate. In this aspect, the association of a fluorochemical with the rigid nanoparticle occurs by polymerization on the nanosized seed particles, and the resulting association of the nanoparticle with the fluorinated polymer such as a fluorinated polyacrylate can occur. Therefore, this seeded emulsion polymerization can be used for the copolymerization of fluorinated acrylates and other fluorinated monomers and co-monomers on the nanoparticles, including along with co-monomers that are not fluorinated. In this aspect, the nanoparticles can be surface-modified with a fluorochemical that comprises or is selected from a polymeric fluoro compound, such as perfluorinated polyacrylates and perfluorinated polyurethanes (core-shell structure). In a typical embodiment, the fluorochemical can be both an oleophobe and a hydrophobe.

Various embodiments and aspects of this disclosure provide that the substrate can be a paper, paperboard or cellulose fiber or cellulose based article wherein the composition imparts the same level of oil and grease repellency with lower levels of elemental fluorine used compared with coatings of traditional fluorochemical resin emulsions. Substrates coated or containing internally, or a combination of both with the present invention have been found to exhibit superior oil and grease repellency with less elemental fluorine than found in coatings of traditional fluorochemical resins. The process of making the substrate with the aqueous dispersion of nanoparticles comprises applying the aqueous dispersion of fluororalkylsilyl surface modified nanoparticles to a substrate; and drying the substrate.

Also disclosed are various articles made from substrates comprising the fluoroalkylsilyl surface-modified nanoparticles provided in this disclosure. More specifically, an article comprises a composition, the composition comprising the fluoroalkylsilyl surface-modified nanoparticle described herein. The nanoparticle can comprises at least one member selected from the group consisting of titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay and mixtures thereof, and the fluoroalkylsilyl moiety can be as disclosed herein. Optionally, the nanoparticle can further comprise a non-fluorinated alkylsilyl moiety also as disclosed herein. Articles can include but are not limited to paper, paperboard, cellulose fiber articles, and other cellulose based articles. When the article is paper, paperboard, cellulose fiber, or cellulose based articles, or includes the optional non-fluorinated alkylsilyl moieties, the nanoparticles can also include silica.

Typically and in one aspect, the articles can comprise a total concentration of fluorine in a range of from about 10 ppm to about 500 ppm by weight (w/w) of exposed substrate, including about 50 ppm to about 300 ppm w/w of exposed substrate. For paper, paperboard, cellulose fiber, or cellulose based articles, the substrate retains the fluoroalkylsilyl surface modified nanoparticle at a weight in the range of from about 0.01% to about 2.0% by weight of the exposed substrate, including from about 0.1% to about 1.0% by weight of the exposed substrate; or wherein the substrate retains elemental fluorine in the range of from about 0.0001% to about 0.10% by weight of the exposed substrate, including from about 0.0001% to about 0.010% by weight of the exposed substrate. In embodiments, the substrate can retain fluoroalkylsilyl surface modified nanoparticles in the range of from about 0.01 to about 3 grams per square meter of surface area, including from about 0.1 to about 2 grams per square meter of surface area.

Definitions. To define more clearly the terms used herein, the following definitions are provided, which are applicable to this disclosure unless otherwise indicated, as long as the definition does not render indefinite or non-enabled any claim to which that definition is applied, for example, by failing to adhere to the conventional rules of chemical valence. If a term is used in this disclosure but is not specifically defined herein, the definition from the IUPAC Compendium of Chemical Terminology, 2^(nd) Ed(1997) can be applied, as long as that definition does not conflict with any other disclosure or definition applied herein, or render indefinite or non-enabled any claim to which that definition is applied. To the extent that any definition or usage provided by any document incorporated herein by reference conflicts with the definition or usage provided herein, the definition or usage provided herein controls.

While compositions and methods are described in terms of “comprising” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components or steps.

While mostly familiar to those versed in the art, the following definitions are provided in the interest of clarity.

As used herein, the term “nanoparticle” is used to describe a multidimensional particle in which one of its dimensions is less than 100 nm in length.

The abbreviation “FAS” is used to mean the class of fluoroalkylsilane reagents used to impart fluorinated organic functionality including, but not limited to, the inorganic particles of this invention. FAS reagents specifically include, but are not limited to structures of the formula: (F(CF₂)_(n)CH₂CH₂)_(m)Si(OR)_(p) where n is 2, 3 or 4; where p is at least 1; where m is at least 1; where m+p=4; and where, for example, R can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or —C(O)CH₃, and the like. Although less preferred for the process of making here disclosed, other structures having perflourinated alkyl terminal functionality should also be understood as being contemplated by this disclosure. FAS reagents can also include structures of the formula: (F(CF₂)_(n)CH₂CH₂)_(m)Si(X)_(p) where n is 2, 3 or 4; where p is at least 1; where m is at least 1; where m+p=4; and where X is a halogen such as chlorine, bromine or iodine. FAS reagents can also include structures of the formula: (F(CF₂)_(n)CH₂CH₂)_(m)SiR′_(p)(X) where n>2, and m+p=3, R′ is methyl or ethyl bonded to the silicon atom and where X is a halogen such as chlorine, bromine or iodine that is bonded to the silicon atom.

The term “clay” as used herein refers to a clay mineral, such as hydrous aluminum phyllosilicate minerals. Clay minerals that can be used in this disclosure include 1:1 and 2:1 clays, and can comprise, consist essentially of, or be selected from smectites (such as montmorillonite, nontronice, sapolite, and the like), kaolins (such as kaolinite, dickite, halloysite, nacrite, and the like), illites (such as illite, clay-micas and the like), chlorites (such as clinochlore, chamosite, nimite, pennantite, and the like), and other minerals and classes such as attapulgites, sepiolites, and the like. These classes include specific clays such as montmorillonite, bentonite, pyrophyllite, hectorite, saponite, sauconite, nontronite, talc, beidellite, volchonskoite, vermiculite, kaolinite, dickite, antigorite, anauxite, indellite, chrysotile, bravaisite, suscovite, paragonite, biotite, corrensite, penninite, donbassite, sudoite, pennine, sepiolite, and polygorskyte. The clay minerals of the invention may be either synthetic or natural and are exfoliated to be capable of forming aqueous micro dispersions. An example of one embodiment of the present invention uses synthetic hectorite clay nanoparticles sold by the trade name Laponite® from Rockwood Additives Ltd. Preferred embodiments of the present invention use Laponite RDS®, Laponite JS®, and Laponite RD®. Therefore, also as used herein, the term “clay” can refer to a clay mineral, such as hydrous aluminum phyllosilicate minerals, and can include 1:1 and 2:1 clays, and can comprise, consist essentially of, or be selected from smectites (such as montmorillonite, nontronice, sapolite, and the like), kaolins (such as kaolinite, dickite, halloysite, nacrite, and the like), illites (such as illite, clay-micas and the like), chlorites (such as clinochlore, chamosite, nimite, pennantite, and the like), and other minerals and classes such as attapulgites, sepiolites, and the like.

An aqueous “dispersion” means a colloidal dispersion, which is a system of finely divided particles of small size, such as nanoparticles, which are uniformly dispersed in a manner such that they are not easily filtered or gravitationally separated.

An aqueous “micro dispersion” is used to describe a dispersion of particles predominately having at least one dimension that is less than about 100 nm in extent.

A “non-solubilized” aqueous micro dispersion is an aqueous micro dispersion that is stable for extended periods of time (two or more months) without water compatible surfactants.

A “layered structure” is one in which the overlap of nanoparticles is observed, and where flat layers or sheets are observed rather than round, globular or clumped aggregate structures.

The term “cellulosic material” or similar terms such as “cellulose fiber material” or “cellulose material” are typically used to refer to paper, paperboard, and cellulose fibers at any stage of their use, for example, being used in the preparation of paper and paperboard.

The term “hydrocarbyl” is used herein in accordance with the definition specified by IUPAC: a univalent group formed by removing a hydrogen atom from a hydrocarbon (that is, a group containing only carbon and hydrogen). Non-limiting examples of hydrocarbyl groups include linear, branched, and cyclic hydrocarbyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, cyclopentyl, vinyl, and the like.

The term “alkyl” group is used herein in accordance with the definition specified by IUPAC: a univalent group derived from an alkane by removal of a hydrogen atom from any carbon atom, having the formula —C_(n)H_(2n+1). Unless otherwise specified, the alkyl can include groups derived from an alkane by removal of a hydrogen atom from a primary, secondary, or tertiary carbon. Therefore, unless otherwise specified, non-limiting examples of alkyl groups include linear, branched, and cyclic alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, cyclopentyl, and the like.

Unless otherwise specified, any carbon-containing group for which the number of carbon atoms is not specified can have, according to proper chemical practice, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 carbon atoms, or any range or combination of ranges between these values. For example, unless otherwise specified, any carbon-containing group can have from 1 to 30 carbon atoms, from 1 to 25 carbon atoms, from 1 to 20 carbon atoms, from 1 to 15 carbon atoms, from 1 to 10 carbon atoms, or from 1 to 5 carbon atoms, and the like. Moreover, other identifiers or qualifying terms may be utilized to indicate the presence or absence of a particular substituent, a particular regiochemistry and/or stereochemistry, or the presence of absence of a branched underlying structure or backbone.

In any application before the United States Patent and Trademark Office, the Abstract of this application is provided for the purpose of satisfying the requirements of 37 C.F.R. §1.72 and the purpose stated in 37 C.F.R. §1.72(b) “to enable the United States Patent and Trademark Office and the public generally to determine quickly from a cursory inspection the nature and gist of the technical disclosure.” Therefore, the Abstract of this application is not intended to be used to construe the scope of the claims or to limit the scope of the subject matter that is disclosed herein. Moreover, any headings that may be employed herein are also not intended to be used to construe the scope of the claims or to limit the scope of the subject matter that is disclosed herein. Any use of the past tense to describe an example that may otherwise be indicated as constructive or prophetic is not intended to reflect that the constructive or prophetic example has actually been carried out.

Applicants reserve the right to proviso out any selection, group, element, or aspect, for example, to limit the scope of any claim to account for a prior disclosure of which Applicants may be unaware.

EXAMPLES

The following examples are provided to illustrate various embodiments of the disclosure and the claims. Unless otherwise specified, reagents were obtained from commercial sources. Standard analytical methods can be used to characterize the compositions.

Various TAPPI testing methods, such as TAPPI Sizing Test Methods including but not limited to T454 om-89 Turpentine Test for Grease Resistance of Paper, T507 cm-85 Grease resistance of Flexible Packaging Materials, T441 om-90 Water Absorptiveness of Sized (Non-Bibulous) Paper and Paperboard (Cobb test), UM 557 Repellency of Paper and Board to Grease, Oil and Waxes (Kit test), can be used.

Performance Tests.

For the following performance tests, all examples were performed using the following protocol. Paper having a basis weight of 34 g/m² was passed through a size-press solution for 15 seconds and dried at 105° C. for 20 seconds on a drum dryer. The dried paper was conditioned for at least 24 hours at 25° C. and 50% humidity before testing. The paper was tested by measuring the contact angle for Castor oil as a function of time using a Rame-Hart goniometer Model 250.

Comparative Example 1

Uncoated paper was tested by measuring the contact angle as described and was found to exhibit an initial oil contact angle of 30 degrees. After 30 seconds contact time, the contact angle decays down to 19 degrees. This changed reflects the strong oil absorption into the paper.

Comparative Example 2

Paper treated in a size-press with a solution of 1% fluorochemicals (Daikin 8112) shows an initial contact angle for Castor oil of 60 degrees. The contact angle remains unchanged after 30 minutes.

Example 3

The same paper as in Comparative Examples 6 and 7 was treated in size-press with a solution 0.5% of modified silica, that is silica nanoparticles modified with silane. After drying, the initial contact angle was determined to be 75 degrees, which remains constant over 30 minutes.

Example 4

The same paper as in Comparative Examples 7 and 8 was pretreated in size-press with a solution 0.4% of silica particles modified with 0.8% cationic polymer (PAE: polyamidoamine epichlorohydrin). After drying, the pre-coated paper was treated with a solution 1% of the same fluorochemical (Daikin 8112). The initial contact angle was 102 degree that remains constant over 30 minutes.

Further attributes, features, and embodiments of the present invention can be understood by reference to the following numbered aspects of the disclosed invention. Reference to disclosure in any of the preceding aspects is applicable to any preceding numbered aspect and to any combination of any number of preceding aspects, as recognized by appropriate antecedent disclosure in any combination of preceding aspects that can be made. The following numbered aspects are provided:

1. A process for making an oil repellent cellulosic material, the process comprising:

a) applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and

b) drying the treated cellulosic substrate to form an oil repellent cellulosic material.

2. The process according to the preceding aspect, wherein the fluorochemical comprises at least one fluoroalkylsilane, ionic fluorochemical, or fluorinated polyacrylate.

3. The process according to any of the preceding aspects, wherein the at least one fluoroalkylsilane has the formula

[F(CF₂)_(n)CH₂CH₂]_(m)Si(OR)_(p),

wherein:

-   -   n is 2, 3, or 4;     -   m is 4-p;     -   p is 1, 2, or 3; and     -   R is a C₁-C₆ hydrocarbyl or —C(O)R¹ wherein R¹ is independently         a C₁-C₆ hydrocarbyl.

4. The process according to any of the preceding aspects, wherein the at least one cationic fluorochemical is selected from an amine, a polyamine, a quaternary ammonium salt, or a combination thereof

5. The process according to any of the preceding aspects, wherein the at least one cationic fluorochemical comprises azetidinium groups.

6. The process according to any of the preceding aspects, wherein the at least one cationic fluorochemical is prepared from the reaction of an epihalohydrin with a compound of the formula:

Z—(X)_(y)—C(O)—NH[(CH₂)_(m)—NH]_(n)—C(O)—(X)_(y)—Z,

wherein

-   -   Z in each occurrence is selected from an acyclic group         C_(s)F_((2s+1)) wherein s is an integer from 3 to 20, and a         cyclic group C_(t)F_((2t−1)) wherein t is an integer from 4 to         6;     -   X in each occurrence is selected from (CH₂)_(p) wherein p is an         integer from 2 to 14, cycloaliphatic radicals, bridged         cycloaliphatic radicals, —CH═CH—(CH₂)_(b)—O—(CH₂)₂—,         —CH₂—CH₂—(CH₂)_(b)—O—(CH₂)₂—, —CH═CH—(CH₂)_(b)—S—(CH₂)₂—,         —CH₂—CH₂—(CH₂)_(b)—S—(CH₂)₂— radicals, where b is zero or an         integer of from 1 to 14, and —SO₂—N(R)—(CH₂)_(q)— radicals,         wherein R is an alkyl radical containing from 1 to 6 carbon         atoms and q is an integer of from 2 to 12;     -   y in each occurrence is 0 or 1;     -   m is an integer of from 2 to 6; and     -   n is an integer of from 2 to 100.

7. The process according to any of the preceding aspects, wherein the ionic fluorochemicals are anionic compounds retained on the nanoparticles with an intermediate cationic polymer.

8. The process according to any of the preceding aspects, wherein the fluorinated polyacrylate is obtained by seeded emulsion polymerization of fluorinated acrylates on the nanoparticles.

9. The process according to any of the preceding aspects, wherein the fluorochemical surface-modified nanoparticles comprise non-fluorinated alkylsilyl moieties having the formula

[H(CH₂)_(x)]_(y)Si(O—)_(z),

wherein:

-   -   x is an integer from 1 to 12;     -   y is 4-z; and     -   z is 1, 2, or 3.

10. The process according to any of the preceding aspects, wherein the cellulosic substrate comprises a component selected from paper, paperboard, and cellulose fiber.

11. The process according to any of the preceding aspects, wherein the fluorochemical surface-modified nanoparticles form a layered structure on the cellulosic substrate having a thickness of less than about 10,000 nanometers.

12. The process according to any of the preceding aspects, wherein the nanoparticle comprises silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay, polystyrene, styrene acrylonitrile (SAN), or combinations thereof

13. The process according to any of the preceding aspects, wherein the nanoparticle comprises silica, natural clay, or synthetic clay.

14. The process according to any of the preceding aspects, wherein the nanoparticle comprises at least one clay selected from smectites, kaolins, illites, chlorites, attapulgites, sepiolites, or combinations thereof.

15. The process according to any of the preceding aspects, wherein the nanoparticle comprises montmorillonite, bentonite, pyrophyllite, hectorite, saponite, sauconite, nontronite, talc, beidellite, volchonskoite, vermiculite, kaolinite, dickite, halloysite, nacrite, antigorite, illite anauxite, indellite, chrysotile, bravaisite, suscovite, paragonite, biotite, corrensite, penninite, donbassite, sudoite, pennine, sepiolite, polygorskyte, clinochlore, chamosite, nimite, pennantite muscovite, phlogopite, or phengite.

16. The process according to any of the preceding aspects, wherein the nanoparticle comprises synthetic hectorite.

17. The process according to any of the preceding aspects, wherein the fluorochemical surface-modified nanoparticles are present in the aqueous dispersion at a concentration from about 0.01% to about 50% by weight of the total composition.

18. The process according to any of the preceding aspects, wherein the homogeneous aqueous dispersion further comprises an emulsion polymer.

19. The process according to any of the preceding aspects, wherein the emulsion polymer is a fluorinated resin emulsion.

20. The process according to any of the preceding aspects, wherein the aqueous dispersion of fluorochemical surface-modified nanoparticles further comprises an alkylated inorganic nanoparticle having no fluorine content.

21. The process according to any of the preceding aspects, wherein the aqueous dispersion of fluoroalkylsilane surface-modified nanoparticles further comprises a wetting agent, an anti-soil agent, an anti-stain agent, a fluorochemical resin, a surfactant, a silicone, an optical brightener, an antibacterial component, an anti-oxidant stabilizer, a coloring agent, a light stabilizer, a UV absorber, starch, polyvinyl alcohol, a retention aid, a wet strength aid, or any combination thereof

22. An article comprising an oil repellent cellulosic material made according to the process according to any of the preceding aspects.

23. The article according to any of the preceding aspect, wherein the concentration of fluorine on the oil repellent cellulosic material is from about 10 ppm to about 500 ppm by weight (w/w).

24. The article according to any of the preceding aspects, wherein the concentration of fluorine on the oil repellent cellulosic material is from about 0.0001% to about 0.10% by weight.

25. The article according to any of the preceding aspects, wherein the fluorochemical surface-modified nanoparticles are present on the oil repellent cellulosic material at a concentration from about 0.01% to about 2.0% by weight.

26. The article according to any of the preceding aspects, wherein the fluorochemical surface-modified nanoparticles are present on the oil repellent cellulosic material from about 0.01 to about 3 grams per square meter (g/m²) of surface area of the oil repellent cellulosic material.

27. A paper or paperboard made according to the process according to any of the preceding aspects.

28. A paper or paperboard treated with a homogeneous aqueous dispersion comprising fluorochemical surface-modified nanoparticles to form an oil-repellent paper or paperboard.

Any suitable combinations of the above described attributes, features, and embodiments set out in the above-numbered aspects of the present invention are also encompssed by this disclosure. Examples of additional aspects and combinations of the above numbered aspects of the invention that are provided herein include, but are not limited to, following numbered aspects:

1. A process for making an oil repellent cellulosic material, the process comprising:

a) applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and

b) drying the treated cellulosic substrate to form an oil repellent cellulosic material.

2. The process according to the preceding aspect, wherein the fluorochemical comprises at least one fluoroalkylsilane, ionic fluorochemical, or fluorinated polyacrylate.

3. The process according to any of the preceding aspects, wherein the at least one fluoroalkylsilane has the formula

[F(CF₂)_(n)CH₂CH₂]_(m)Si(OR)_(p),

wherein:

-   -   n is 2, 3, or 4;     -   m is 4-p;     -   p is 1, 2, or 3; and     -   R is a C₁-C₆ hydrocarbyl or —C(O)R¹ wherein R¹ is independently         a C₁-C₆ hydrocarbyl.

4. The process according to any of the preceding aspects, wherein the at least one ionic fluorochemical is selected from an amine, a polyamine, a quaternary ammonium salt, a cationic fluorochemical comprising azetidinium groups, or a combination thereof

5. The process according to any of the preceding aspects, wherein the at least one ionic fluorochemical is prepared from the reaction of an epihalohydrin with a compound of the formula:

Z—(X)_(y)—C(O)—NH[(CH₂)_(m)—NH]_(n)—C(O)—(X)_(y)—Z,

wherein

-   -   Z in each occurrence is selected from an acyclic group         C_(s)F_((2s+1)) wherein s is an integer from 3 to 20, and a         cyclic group C_(t)F_((2t−1)) wherein t is an integer from 4 to         6;     -   X in each occurrence is selected from (CH₂)_(p) wherein p is an         integer from 2 to 14, cycloaliphatic radicals, bridged         cycloaliphatic radicals, —CH═CH—(CH₂)_(b)—O—(CH₂)₂—,         —CH₂—CH₂—(CH₂)_(b)—O—(CH₂)₂—, —CH═CH—(CH₂)_(b)—S—(CH₂)₂—,         —CH₂—CH₂—(CH₂)_(b)—S—(CH₂)₂— radicals, where b is zero or an         integer of from 1 to 14, and —SO₂—N(R)—(CH₂)_(q)— radicals,         wherein R is an alkyl radical containing from 1 to 6 carbon         atoms and q is an integer of from 2 to 12;     -   y in each occurrence is 0 or 1;     -   m is an integer of from 2 to 6; and     -   n is an integer of from 2 to 100.

6. The process according to any of the preceding aspects, wherein the ionic fluorochemicals are anionic compounds retained on the nanoparticles with an intermediate cationic polymer.

7. The process according to any of the preceding aspects, wherein the fluorochemical surface-modified nanoparticles comprise non-fluorinated alkylsilyl moieties having the formula

[H(CH₂)_(x)]_(y)Si(O—)_(z),

wherein:

-   -   x is an integer from 1 to 12;     -   y is 4-z; and     -   z is 1, 2, or 3.

8. The process according to any of the preceding aspects, wherein the cellulosic substrate comprises a component selected from paper, paperboard, and cellulose fiber.

9. The process according to any of the preceding aspects, wherein the fluorochemical surface-modified nanoparticles form a layered structure on the cellulosic substrate having a thickness of less than about 10,000 nanometers.

10. The process according to any of the preceding aspects, wherein the nanoparticle comprises silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay, polystyrene, styrene acrylonitrile (SAN), or combinations thereof

11. The process according to any of the preceding aspects, wherein the nanoparticle comprises at least one clay selected from smectites, kaolins, illites, chlorites, attapulgites, sepiolites, or combinations thereof.

12. The process according to any of the preceding aspects, wherein the nanoparticle comprises montmorillonite, bentonite, pyrophyllite, hectorite, saponite, sauconite, nontronite, talc, beidellite, volchonskoite, vermiculite, kaolinite, dickite, halloysite, nacrite, antigorite, illite anauxite, indellite, chrysotile, bravaisite, suscovite, paragonite, biotite, corrensite, penninite, donbassite, sudoite, pennine, sepiolite, polygorskyte, clinochlore, chamosite, nimite, pennantite muscovite, phlogopite, synthetic hectorite, or phengite.

13. The process according to any of the preceding aspects, wherein the fluorochemical surface-modified nanoparticles are present in the aqueous dispersion at a concentration from about 0.01% to about 50% by weight of the total composition.

14. The process according to any of the preceding aspects, wherein the homogeneous aqueous dispersion further comprises an emulsion polymer or a fluorinated resin emulsion.

15. The process according to any of the preceding aspects, wherein the aqueous dispersion of fluorochemical surface-modified nanoparticles further comprises a wetting agent, an anti-soil agent, an anti-stain agent, a fluorochemical resin, a surfactant, a silicone, an optical brightener, an antibacterial component, an anti-oxidant stabilizer, a coloring agent, a light stabilizer, a UV absorber, starch, polyvinyl alcohol, a retention aid, a wet strength aid, an alkylated inorganic nanoparticle having no fluorine content. or any combination thereof.

16. A paper or paperboard made according to any of the preceding process aspects.

17. An article comprising an oil repellent cellulosic material made by a process comprising:

a) applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and

b) drying the treated cellulosic substrate to form an oil repellent cellulosic material; or made according to any of the preceding process aspects.

18. The article made according to any of the preceding process aspects, wherein the concentration of fluorine on the oil repellent cellulosic material is either from about 10 ppm to about 500 ppm by weight (w/w), or from about 0.0001% to about 0.10% by weight.

19. The article made according to any of the preceding process aspects, wherein the fluorochemical surface-modified nanoparticles are present on the oil repellent cellulosic material at a concentration of either from about 0.01% to about 2.0% by weight, or from about 0.01 to about 3 grams per square meter (g/m²) of surface area of the oil repellent cellulosic material.

20. A paper or paperboard treated with a homogeneous aqueous dispersion comprising fluorochemical surface-modified nanoparticles to form an oil-repellent paper or paperboard.

This invention has been described above with reference to the various aspects of the disclosed oil repellency and methods of making paper and paperboard having improved oil repellency. Obvious modifications and alterations will occur to others upon reading and understanding the proceeding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the claims. 

We claim:
 1. A process for making an oil repellent cellulosic material, the process comprising: a) applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and b) drying the treated cellulosic substrate to form an oil repellent cellulosic material.
 2. The process of claim 1, wherein the fluorochemical comprises at least one fluoroalkylsilane, ionic fluorochemical, or fluorinated polyacrylate.
 3. The process of claim 2, wherein the at least one fluoroalkylsilane has the formula [F(CF₂)_(n)CH₂CH₂]_(m)Si(OR)_(p), wherein: n is 2, 3, or 4; m is 4-p; p is 1, 2, or 3; and R is a C₁-C₆ hydrocarbyl or —C(O)R¹ wherein R¹ is independently a C₁-C₆ hydrocarbyl.
 4. The process of claim 2, wherein the at least one ionic fluorochemical is selected from an amine, a polyamine, a quaternary ammonium salt, a cationic fluorochemical comprising azetidinium groups, or a combination thereof.
 5. The process of claim 2, wherein the at least one ionic fluorochemical is prepared from the reaction of an epihalohydrin with a compound of the formula: Z—(X)_(y)—C(O)—NH[(CH₂)_(m)—NH]_(n)—C(O)—(X)_(y)—Z, wherein Z in each occurrence is selected from an acyclic group C_(s)F_((2s+1)) wherein s is an integer from 3 to 20, and a cyclic group C_(t)F_((2t−1)) wherein t is an integer from 4 to 6; X in each occurrence is selected from (CH₂)_(p) wherein p is an integer from 2 to 14, cycloaliphatic radicals, bridged cycloaliphatic radicals, —CH═CH—(CH₂)_(b)—O—(CH₂)₂—, —CH₂—CH₂—(CH₂)_(b)—O—(CH₂)₂—, —CH═CH—(CH₂)_(b)—S—(CH₂)₂—, —CH₂—CH₂—(CH₂)_(b)—S—(CH₂)₂— radicals, where b is zero or an integer of from 1 to 14, and —SO₂—N(R)—(CH₂)_(q)— radicals, wherein R is an alkyl radical containing from 1 to 6 carbon atoms and q is an integer of from 2 to 12; y in each occurrence is 0 or 1; m is an integer of from 2 to 6; and n is an integer of from 2 to
 100. 6. The process of claim 2, wherein the ionic fluorochemicals are anionic compounds retained on the nanoparticles with an intermediate cationic polymer.
 7. The process of claim 1, wherein the fluorochemical surface-modified nanoparticles comprise non-fluorinated alkylsilyl moieties having the formula [H(CH₂)_(x)]_(y)Si(O—)_(z), wherein: x is an integer from 1 to 12; y is 4-z; and z is 1, 2, or
 3. 8. The process of claim 1, wherein the cellulosic substrate comprises a component selected from paper, paperboard, and cellulose fiber.
 9. The process of claim 1, wherein the fluorochemical surface-modified nanoparticles form a layered structure on the cellulosic substrate having a thickness of less than about 10,000 nanometers.
 10. The process of claim 1, wherein the nanoparticle comprises silica, titania, zirconia, layered magnesium silicate, aluminosilicate, natural clay, synthetic clay, polystyrene, styrene acrylonitrile (SAN), or combinations thereof.
 11. The process of claim 1, wherein the nanoparticle comprises at least one clay selected from smectites, kaolins, illites, chlorites, attapulgites, sepiolites, or combinations thereof.
 12. The process of claim 1, wherein the nanoparticle comprises montmorillonite, bentonite, pyrophyllite, hectorite, saponite, sauconite, nontronite, talc, beidellite, volchonskoite, vermiculite, kaolinite, dickite, halloysite, nacrite, antigorite, illite anauxite, indellite, chrysotile, bravaisite, suscovite, paragonite, biotite, corrensite, penninite, donbassite, sudoite, pennine, sepiolite, polygorskyte, clinochlore, chamosite, nimite, pennantite muscovite, phlogopite, synthetic hectorite, or phengite.
 13. The process of claim 1, wherein the fluorochemical surface-modified nanoparticles are present in the aqueous dispersion at a concentration from about 0.01% to about 50% by weight of the total composition.
 14. The process of claim 1, wherein the homogeneous aqueous dispersion further comprises an emulsion polymer or a fluorinated resin emulsion.
 15. The process of claim 1, wherein the aqueous dispersion of fluorochemical surface-modified nanoparticles further comprises a wetting agent, an anti-soil agent, an anti-stain agent, a fluorochemical resin, a surfactant, a silicone, an optical brightener, an antibacterial component, an anti-oxidant stabilizer, a coloring agent, a light stabilizer, a UV absorber, starch, polyvinyl alcohol, a retention aid, a wet strength aid, an alkylated inorganic nanoparticle having no fluorine content. or any combination thereof.
 16. A paper or paperboard made according to the process of claim
 1. 17. An article comprising an oil repellent cellulosic material made by a process comprising: a) applying a homogeneous aqueous dispersion of fluorochemical surface-modified nanoparticles to a cellulosic substrate to form a treated cellulosic substrate; and b) drying the treated cellulosic substrate to form an oil repellent cellulosic material.
 18. The article of claim 17, wherein the concentration of fluorine on the oil repellent cellulosic material is either from about 10 ppm to about 500 ppm by weight (w/w), or from about 0.0001% to about 0.10% by weight.
 19. The article of claim 17, wherein the fluorochemical surface-modified nanoparticles are present on the oil repellent cellulosic material at a concentration of either from about 0.01% to about 2.0% by weight, or from about 0.01 to about 3 grams per square meter (g/m²) of surface area of the oil repellent cellulosic material.
 20. A paper or paperboard treated with a homogeneous aqueous dispersion comprising fluorochemical surface-modified nanoparticles to form an oil-repellent paper or paperboard. 